package com.green.common;

import java.util.Arrays;
import java.util.Random;

public class Base64Encoder
{
  private static final char[] intToBase64 = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' };

  private static final char[] intToAltBase64 = { '!', '"', '#', '$', '%', '&', '\'', '(', ')', ',', '-', '.', ':', ';', '<', '>', '@', '[', ']', '^', '`', '_', '{', '|', '}', '~', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '?' };

  private static final byte[] base64ToInt = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 };

  private static final byte[] altBase64ToInt = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, -1, 62, 9, 10, 11, -1, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 12, 13, 14, -1, 15, 63, 16, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 17, -1, 18, 19, 21, 20, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 22, 23, 24, 25 };

  public static String byteArrayToBase64(byte[] a)
  {
    return byteArrayToBase64(a, false);
  }

  public static String byteArrayToAltBase64(byte[] a)
  {
    return byteArrayToBase64(a, true);
  }

  private static String byteArrayToBase64(byte[] a, boolean alternate) {
    int aLen = a.length;
    int numFullGroups = aLen / 3;
    int numBytesInPartialGroup = aLen - 3 * numFullGroups;
    int resultLen = 4 * ((aLen + 2) / 3);
    StringBuffer result = new StringBuffer(resultLen);
    char[] intToAlpha = alternate ? intToAltBase64 : intToBase64;

    int inCursor = 0;
    for (int i = 0; i < numFullGroups; i++) {
      int byte0 = a[(inCursor++)] & 0xFF;
      int byte1 = a[(inCursor++)] & 0xFF;
      int byte2 = a[(inCursor++)] & 0xFF;
      result.append(intToAlpha[(byte0 >> 2)]);
      result.append(intToAlpha[(byte0 << 4 & 0x3F | byte1 >> 4)]);
      result.append(intToAlpha[(byte1 << 2 & 0x3F | byte2 >> 6)]);
      result.append(intToAlpha[(byte2 & 0x3F)]);
    }

    if (numBytesInPartialGroup != 0) {
      int byte0 = a[(inCursor++)] & 0xFF;
      result.append(intToAlpha[(byte0 >> 2)]);
      if (numBytesInPartialGroup == 1) {
        result.append(intToAlpha[(byte0 << 4 & 0x3F)]);
        result.append("==");
      }
      else {
        int byte1 = a[(inCursor++)] & 0xFF;
        result.append(intToAlpha[(byte0 << 4 & 0x3F | byte1 >> 4)]);
        result.append(intToAlpha[(byte1 << 2 & 0x3F)]);
        result.append('=');
      }

    }

    return result.toString();
  }

  public static byte[] base64ToByteArray(String s)
  {
    return base64ToByteArray(s, false);
  }

  public static byte[] altBase64ToByteArray(String s)
  {
    return base64ToByteArray(s, true);
  }

  private static byte[] base64ToByteArray(String s, boolean alternate) {
    byte[] alphaToInt = alternate ? altBase64ToInt : base64ToInt;
    int sLen = s.length();
    int numGroups = sLen / 4;
    if (4 * numGroups != sLen) {
      throw new IllegalArgumentException("String length must be a multiple of four.");
    }
    int missingBytesInLastGroup = 0;
    int numFullGroups = numGroups;
    if (sLen != 0) {
      if (s.charAt(sLen - 1) == '=') {
        missingBytesInLastGroup++;
        numFullGroups--;
      }
      if (s.charAt(sLen - 2) == '=')
        missingBytesInLastGroup++;
    }
    byte[] result = new byte[3 * numGroups - missingBytesInLastGroup];

    int inCursor = 0; int outCursor = 0;
    for (int i = 0; i < numFullGroups; i++) {
      int ch0 = base64toInt(s.charAt(inCursor++), alphaToInt);
      int ch1 = base64toInt(s.charAt(inCursor++), alphaToInt);
      int ch2 = base64toInt(s.charAt(inCursor++), alphaToInt);
      int ch3 = base64toInt(s.charAt(inCursor++), alphaToInt);
      result[(outCursor++)] = (byte)(ch0 << 2 | ch1 >> 4);
      result[(outCursor++)] = (byte)(ch1 << 4 | ch2 >> 2);
      result[(outCursor++)] = (byte)(ch2 << 6 | ch3);
    }

    if (missingBytesInLastGroup != 0) {
      int ch0 = base64toInt(s.charAt(inCursor++), alphaToInt);
      int ch1 = base64toInt(s.charAt(inCursor++), alphaToInt);
      result[(outCursor++)] = (byte)(ch0 << 2 | ch1 >> 4);

      if (missingBytesInLastGroup == 1) {
        int ch2 = base64toInt(s.charAt(inCursor++), alphaToInt);
        result[(outCursor++)] = (byte)(ch1 << 4 | ch2 >> 2);
      }

    }

    return result;
  }

  private static int base64toInt(char c, byte[] alphaToInt)
  {
    int result = alphaToInt[c];
    if (result < 0)
      throw new IllegalArgumentException("Illegal character " + c);
    return result;
  }

  public static void main(String[] args)
  {
    int numRuns = Integer.parseInt(args[0]);
    int numBytes = Integer.parseInt(args[1]);
    Random rnd = new Random();
    for (int i = 0; i < numRuns; i++)
      for (int j = 0; j < numBytes; j++) {
        byte[] arr = new byte[j];
        for (int k = 0; k < j; k++) {
          arr[k] = (byte)rnd.nextInt();
        }
        String s = byteArrayToBase64(arr);
        byte[] b = base64ToByteArray(s);
        if (!Arrays.equals(arr, b)) {
          System.out.println("Dismal failure!");
        }
        s = byteArrayToAltBase64(arr);
        b = altBase64ToByteArray(s);
        if (!Arrays.equals(arr, b))
          System.out.println("Alternate dismal failure!");
      }
  }
}
